This invention concerns diesel internal combustion engines and, more particularly, such engines with a device for temperature-dependent adjustment of fuel injection start-up.
As German Offenlegungsschrift No. 26 53 046 reveals, pollutant emission from a diesel engine can be favorably influenced by appropriate adjustment to starting fuel injection. A device disclosed therein utilizes performance characteristics of the diesel engine, including rpms, load, and an engine temperature, to control the start of the injection.
Another prior art reference is EP 0 137 316 A1 which describes how to adjust the start of fuel injection in a direction of earlier injection for cold diesel engines and during hot-running of such engines. A thermostat determines the temperature.
However, it has not been possible heretofore to reduce both a hydrocarbon component and a NO.sub.x component in the pollutant emission from a diesel engine to low amounts. While the NO.sub.x content diminishes by delaying the start of injection, the hydrocarbon content increases. Unless other values of individual engine parameters require a different adjustment, an injection starting time, with due consideration for fuel consumption, usually falls in an area in which both the hydrocarbon and the NO.sub.x components represent moderate amounts in a waste gas. Decreasing the NO.sub.x content by delaying the start of injection is thus limited by a steep increase in the hydrocarbon emission.